Novel aspects of orbital fibroblast pathology

Extreme Tolerance of Extraocular Muscles to Diseases and Aging: Why and How?

The extraocular muscles (EOMs) possess unique characteristics that set them apart from other skeletal muscles. These muscles, responsible for eye movements, exhibit remarkable resistance to various muscular dystrophies and aging, presenting a significant contrast to the vulnerability of skeletal muscles to these conditions. In this review, we delve into the cellular and molecular underpinnings of the distinct properties of EOMs. We explore their structural complexity, highlighting differences in fiber types, innervation patterns, and developmental origins. Notably, EOM fibers express a diverse array of myosin heavy-chain isoforms, retaining embryonic forms into adulthood. Moreover, their motor innervation is characterized by a high ratio of nerve fibers to muscle fibers and the presence of unique neuromuscular junctions. These features contribute to the specialized functions of EOMs, including rapid and precise eye movements. Understanding the mechanisms behind the resilience of EOMs to disease and aging may offer insights into potential therapeutic strategies for treating muscular dystrophies and myopathies affecting other skeletal muscles.

Surgical treatment of orbital tumors in a single center: Analysis and results

Background

Orbital tumors, arising within the bony orbit and its contents, present diverse challenges due to their varied origins and complex anatomical context. These tumors, classified as primary, secondary, or metastatic, are further subdivided into intraconal and extraconal based on their relationship with the muscle cone. This classification significantly influences surgical approach and management. This study highlights surgical experiences with orbital tumors, underscoring the importance of tailored surgical approaches based on the lesion's site and its proximity to the optic nerve.

Methods

This retrospective study at the National Institute of Cancer's Head and Neck Department (2005-2014) analyzed 29 patients with orbital tumors treated with surgery, radiotherapy, chemotherapy, or combinations of them. Patient demographics, tumor characteristics, and treatment responses were evaluated using computed tomography (CT), magnetic resonance imaging, and positron emission tomography-CT imaging. Malignant tumors often required orbital exenteration and reconstruction, highlighting the study's commitment to advancing orbital tumor treatment.

Results

29 patients (18 females and 11 males, age 18-88 years, mean 53.5 years) with orbital tumors exhibited symptoms such as decreased vision and exophthalmos. Tumors included primary lesions like choroidal melanoma and secondary types like epidermoid carcinoma. Treatments varied, involving a multidisciplinary team for surgical approaches like exenteration, with follow-up from 1 to 9 years. Radiotherapy and chemotherapy were used for specific cases.

Conclusion

Our study underscores the need for a multidisciplinary approach in treating orbital tumors, involving various surgical specialists and advanced technologies like neuronavigation for tailored treatment. The integration of surgery with radiotherapy and chemotherapy highlights the effectiveness of multidimensional treatment strategies.

Fibrocyte Participation in Thyroid-Associated Ophthalmopathy Suggests New Approaches to Therapy

PURPOSE

Review the historical context of research and changing therapeutic landscape of thyroid-associated ophthalmopathy (TAO) by focusing on the relationship between TAO, CD34+ fibrocytes, thyrotropin receptor (TSHR), and insulin-like growth factor-I receptor (IGF-IR).

METHODS

A literature review using search terms, including fibrocytes, IGF-IR, TSHR, TAO, and thyroid eye disease.

RESULTS

The mechanisms involved in TAO have been partially identified. Substantial progress has been made over several decades, including 1) recognizing the interplay between the professional immune system and orbital tissues; 2) TSHR and IGF-IR act interdependently in mediating the pathogenesis of TAO; 3) Multiple cytokines and specific immune cells are involved in activating and remodeling orbital tissue; 4) Recognition of these mechanisms is allowing the development of target therapies such as teprotumumab, a monoclonal antibody IGF-IR inhibitor approved by the US Food and drug administration for treatment of TAO; and 5) It appears that teprotumumab acts on the systemic immune system peripheral to the orbit.

CONCLUSION

Additional molecules targeting IGF-IR and other plausible disease mechanisms are currently under development. This activity in the TAO therapeutic space portends even greater improvements in patient care.

Mechanisms in Graves Eye Disease: Apoptosis as the End Point of Insulin-Like Growth Factor 1 Receptor Inhibition

Background: Graves' eye disease, also called Graves' orbitopathy (GO), is a potentially debilitating autoimmune disease associated with retro-orbital inflammation and tissue expansion, involving both fibroblasts and adipocytes, resulting in periorbital edema, worsening proptosis, and muscle dysfunction with diplopia and may ultimately threaten sight. Accumulating evidence has indicated that autoantibodies to the thyrotropin receptor (TSHR), which induce the hyperthyroidism of Graves' disease, also help mediate the pathogenesis of the eye disease in susceptible individuals through TSHR expression on retro-orbital cells. Since it has long been known that the effects of insulin-like growth factor 1 (IGF-1) and thyrotropin are additive, recent clinical trials with a human monoclonal IGF-1 receptor blocking antibody (teprotumumab; IGF-1R-B-monoclonal antibody [mAb]) have demonstrated its ability to induce significant reductions in proptosis, diplopia, and clinical activity scores in patients with GO. However, the molecular mechanisms by which such an antibody achieves this result is unclear. Methods: We have used Li-Cor In-Cell Western, Western blot, and immunohistochemistry to define levels of different proteins in mouse and human fibroblast cells. Proteomic array was also used to define pathway signaling molecules. Using CCK-8 and BrdU cell proliferation ELISA, we have analyzed proliferative response of these cells to different antibodies. Results: We now show that a stimulating TSHR antibody was able to induce phosphorylation of the IGF-1R and initiate both TSHR and IGF-1R signaling in mouse and human fibroblasts. IGF-1R-B-mAb (1H7) inhibited all major IGF-1R signaling cascades and also reduced TSHR signaling. This resulted in the antibody-induced suppression of autophagy as shown by inhibition of multiple autophagy-related proteins (Beclin1, LC3a, LC3b, p62, and ULK1) and the induction of cell death by apoptosis as evidenced by activation of cleaved caspase 3, FADD, and caspase 8. Furthermore, this IGF-1R-blocking mAb suppressed serum-induced perkin and pink mitophagic proteins. Conclusions: Our observations clearly indicated that stimulating TSHR antibodies were able to enhance IGF-1R activity and contribute to retro-orbital cellular proliferation and inflammation. In contrast, an IGF-1R-B-mAb was capable of suppressing IGF-1R signaling leading to retro-orbital fibroblast/adipocyte death through the cell-extrinsic pathway of apoptosis. This is likely the major mechanism involved in proptosis reduction in patients with Graves' eye disease treated by IGF-1R inhibition.

The Potential Role of Osteopontin in the Pathogenesis of Graves' Ophthalmopathy

Purpose

The aim of this study is to evaluate the expression of osteopontin (OPN) and its relationship with relative cytokines in patients with Graves’ ophthalmopathy (GO), and to observe the effect of OPN on orbital fibroblasts (OFs) proliferation, migration, and the expression of relative cytokines, as well as the signaling pathways involved in its effect.

Methods

The orbital adipose connective tissue was obtained from 24 patients with GO (12 cases of active GO, and 12 cases of inactive GO) and 12 healthy controls. OFs were isolated from orbital tissues obtained from patients with active GO who were undergoing orbital decompression surgery. Quantitative PCR and Western blot were performed to detect RNA and protein expression. The proliferation and cell migration rates of OFs were measured by methylthiazol tetrazolium (MTT) and the cell scratch test. Signaling pathway inhibitors, such as OPN monoclonal antibody 1A12, ERK1/2 inhibitor PD98059, and PI3K inhibitor LY294002, were applied to determine the involved pathways.

Results

The mRNA and protein levels of OPN were increased in orbital adipose connective tissue from patients with active GO than those from patients with inactive GO (2.83-fold increase, P < 0.001; 1.91-fold increase, P < 0.05). The OPN mRNA level was positively correlated with CD40 ligand (CD40L) and hyaluronan synthases 2 (HAS2) mRNA in patients with GO. OPN promoted proliferation and migration rate of OFs and induced vascular endothelial growth factor (VEGF) and collagen I mRNA expression, and the effects were inhibited by 1A12 or LY294002.

Conclusions

OPN in orbital adipose connective tissues were significantly increase in active GO, and there were significant correlations of OPN with CD40L and HAS2 mRNA levels in patients with GO. OPN promoted proliferation and migration of OFs and induced VEGF and collagen I mRNA expression in OFs through PI3K/Akt signaling pathway. This suggested a role for OPN in the pathogenesis of GO through the activation of OFs.

Pharmacokinetics and Exposure-Response Relationship of Teprotumumab, an Insulin-Like Growth Factor-1 Receptor-Blocking Antibody, in Thyroid Eye Disease

Background and Objective

Thyroid eye disease (TED) is characterized by inflammation/expansion of orbital tissues, proptosis, and diplopia. Teprotumumab is the first US Food and Drug Administration-approved therapy for TED, administered as an initial intravenous infusion of 10 mg/kg followed by 20 mg/kg every 3 weeks for an additional seven infusions. The objective of this article is to discuss the pharmacokinetics and exposure-response profile for teprotumumab in patients with TED.

Methods

A population pharmacokinetic analysis was performed to characterize pharmacokinetics and select dosing in patients with TED. Exposure-response was evaluated for efficacy (proptosis response, clinical activity score categorical response, and diplopia response) and safety (hyperglycemia, muscle spasms, and hearing impairment) parameters.

Results

Teprotumumab pharmacokinetics was linear in patients with TED, with low systemic clearance (0.334 L/day), low volume of distribution (3.9 and 4.2 L for the central and peripheral compartment, respectively), and a long elimination half-life (19.9 days). The approved dosing regimen provided > 20 µg/mL for > 90% insulin-like growth factor 1 receptor saturation throughout the dosing interval. Model-predicted mean (± standard deviation) steady-state area under the concentration-time curve, peak, and trough concentrations in patients with TED were 131 (± 30.9) mg∙h/mL, 643 (± 130) µg/mL, and 157 (± 50.6) µg/mL, respectively. Female patients had a 15% higher steady-state peak concentration but a similar steady-state area under the concentration-time curve vs male patients. No other covariates affected teprotumumab pharmacokinetics. No meaningful correlations between teprotumumab exposures and efficacy or safety parameters were observed.

Conclusions

Teprotumumab pharmacokinetics was well characterized in patients with TED, and generally consistent with other IgG1 antibodies. Efficacy was consistent across the exposure range with a well-tolerated safety profile supporting the current dose regimen for patients with TED.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40262-021-01003-3.

Protein tyrosine phosphatase 1B as a therapeutic target for Graves' orbitopathy in an in vitro model

Graves' orbitopathy (GO) is characterised in early stages by orbital fibroblast inflammation, which can be aggravated by oxidative stress and often leads to fibrosis. Protein tyrosine protein 1B (PTP1B) is a regulator of inflammation and a therapeutic target in diabetes. We investigated the role of PTP1B in the GO mechanism using orbital fibroblasts from GO and healthy non-GO subjects. After 24 hours of transfection with PTPN1 siRNA, the fibroblasts were exposed to interleukin (IL)-1β, cigarette smoke extract (CSE), H2O2, and transforming growth factor (TGF)-β stimulations. Inflammatory cytokines and fibrosis-related proteins were analysed using western blotting and/or enzyme-linked immunosorbent assay (ELISA). Reactive oxygen species (ROS) release was detected using an oxidant-sensitive fluorescent probe. IL-1β, tumor necrosis factor (TNF)-α, bovine thyroid stimulating hormone (bTSH), high-affinity human stimulatory monoclonal antibody of TSH receptor (M22), and insulin-like growth factor-1 (IGF-1) significantly increased PTP1B protein production in GO and non-GO fibroblasts. PTPN1 silencing significantly blocked IL-1β-induced inflammatory cytokine production, CSE- and H2O2-induced ROS synthesis, and TGF-β-induced expression of collagen Iα, α-smooth muscle actin (SMA), and fibronectin in GO fibroblasts. Silencing PTPN1 also decreased phosphorylation levels of Akt, p38, and c-Jun N-terminal kinase (JNK) and endoplasmic reticulum (ER)-stress response proteins in GO cells. PTP1B may be a potential therapeutic target of anti-inflammatory, anti-oxidant and anti-fibrotic treatment of GO.

Teprotumumab for the Treatment of Active Thyroid Eye Disease

BACKGROUND

Thyroid eye disease is a debilitating, disfiguring, and potentially blinding periocular condition for which no Food and Drug Administration-approved medical therapy is available. Strong evidence has implicated the insulin-like growth factor I receptor (IGF-IR) in the pathogenesis of this disease.

METHODS

In a randomized, double-masked, placebo-controlled, phase 3 multicenter trial, we assigned patients with active thyroid eye disease in a 1:1 ratio to receive intravenous infusions of the IGF-IR inhibitor teprotumumab (10 mg per kilogram of body weight for the first infusion and 20 mg per kilogram for subsequent infusions) or placebo once every 3 weeks for 21 weeks; the last trial visit for this analysis was at week 24. The primary outcome was a proptosis response (a reduction in proptosis of ≥2 mm) at week 24. Prespecified secondary outcomes at week 24 were an overall response (a reduction of ≥2 points in the Clinical Activity Score plus a reduction in proptosis of ≥2 mm), a Clinical Activity Score of 0 or 1 (indicating no or minimal inflammation), the mean change in proptosis across trial visits (from baseline through week 24), a diplopia response (a reduction in diplopia of ≥1 grade), and the mean change in overall score on the Graves' ophthalmopathy-specific quality-of-life (GO-QOL) questionnaire across trial visits (from baseline through week 24; a mean change of ≥6 points is considered clinically meaningful).

RESULTS

A total of 41 patients were assigned to the teprotumumab group and 42 to the placebo group. At week 24, the percentage of patients with a proptosis response was higher with teprotumumab than with placebo (83% [34 patients] vs. 10% [4 patients], P<0.001), with a number needed to treat of 1.36. All secondary outcomes were significantly better with teprotumumab than with placebo, including overall response (78% of patients [32] vs. 7% [3]), Clinical Activity Score of 0 or 1 (59% [24] vs. 21% [9]), the mean change in proptosis (-2.82 mm vs. -0.54 mm), diplopia response (68% [19 of 28] vs. 29% [8 of 28]), and the mean change in GO-QOL overall score (13.79 points vs. 4.43 points) (P≤0.001 for all). Reductions in extraocular muscle, orbital fat volume, or both were observed in 6 patients in the teprotumumab group who underwent orbital imaging. Most adverse events were mild or moderate in severity; two serious events occurred in the teprotumumab group, of which one (an infusion reaction) led to treatment discontinuation.

CONCLUSIONS

Among patients with active thyroid eye disease, teprotumumab resulted in better outcomes with respect to proptosis, Clinical Activity Score, diplopia, and quality of life than placebo; serious adverse events were uncommon. (Funded by Horizon Therapeutics; OPTIC ClinicalTrials.gov number, NCT03298867, and EudraCT number, 2017-002763-18.).

Thyroid-associated ophthalmopathy: Emergence of teprotumumab as a promising medical therapy

Thyroid-associated ophthalmopathy (TAO) remains a vexing autoimmune component of Graves' disease that can diminish the quality of life as a consequence of its impact on visual function, physical appearance and emotional well-being. Because of its relative rarity and variable presentation, the development of highly effective and well-tolerated medical therapies for TAO has been slow relative to other autoimmune diseases. Contributing to the barriers of greater insight into TAO has been the historical absence of high-fidelity preclinical animal models. Despite these challenges, several agents, most developed for treatment of other diseases, have found their way into consideration for use in active TAO through repurposing. Among these, teprotumumab is a fully human inhibitory monoclonal antibody against the insulin-like growth factor I receptor. It has shown remarkable effectiveness in moderate to severe, active TAO in two completed multicenter, double masked, and placebo controlled clinical trials. The drug exhibits a favorable safety profile. Teprotumumab has recently been approved by the U.S. F.D.A, and may rapidly become the first line therapy for this disfiguring and potentially blinding condition.

Efficacy and safety of pulsed intravenous methylprednisolone in early active thyroid eye disease

Introduction: The mainstay of therapy for active inflammatory phase of thyroid eye disease (TED) is immunosuppression. Patients in our centre with early active TED are treated with pulsed intravenous methylprednisolone (IVMP). Two different protocols are offered in our centre: High dose (1g/day for 3 days, monthly for 6 months), or EUGOGO protocol (500 mg weekly for six weeks, followed by 250 mg weekly for the next 6 weeks). Methods: A prospective cohort study of patients undergoing the two IVMP protocols was performed from January 2009 to May 2015. Main outcome measures were improvement of Clinical Activity Score (CAS) and International Thyroid Eye Disease (ITEDS) - VISA Inflammatory Index. Results: We had a total of 63 patients. Mean age was 43.1 ± 13.1years, females comprised 49.2% (n = 31), and 31 (49.2%) had a positive smoking history. Following IVMP, 65.0% (n = 41) had good response, 31.7% (n = 20) partial, and 3.3% (n = 2) poor. There were significant differences (p < 0.001) in CAS and ITEDS scores between pre-IVMP and post-IVMP visits, for both protocols. A higher proportion of patients receiving the modified EUGOGO protocol (58.3%) had persistent activity and required additional immunosuppression compared to those who underwent the high dose protocol (33.3%). Mild side effects were experienced by 5 (7.9%) and 3 (4.8%) patients at 3 and 6 months, respectively. There were no severe side effects, cardiovascular events or liver failure. Conclusion: With adequate screening and follow-up, six repeated cycles of high dose pulsed IVMP is an effective treatment for TED and can significantly reduce the morbidity associated with this debilitating condition. None of the 51 patients from the high dose protocol met with any serious side effects.

Celastrol inhibits IL-1β-induced inflammation in orbital fibroblasts through the suppression of NF-κB activity

Graves' disease is an autoimmune disease of the thyroid gland, which is characterized by hyperthyroidism, diffuse goiter and Graves' ophthalmopathy (GO). Although several therapeutic strategies for the treatment of GO have been developed, the effectiveness and the safety profile of these therapies remain to be fully elucidated. Therefore, examination of novel GO therapies remains an urgent requirement. Celastrol, a triterpenoid isolated from traditional Chinese medicine, is a promising drug for the treatment of various inflammatory and autoimmune diseases. CCK‑8 and apoptosis assays were performed to investigate cytotoxicity of celastrol and effect on apoptosis on orbital fibroblasts. Reverse transcription‑polymerase chain reaction, western blotting and ELISAs were performed to examine the effect of celastrol on interleukin (IL)‑1β‑induced inflammation in orbital fibroblasts from patients with GO. The results demonstrated that celastrol significantly attenuated the expression of IL‑6, IL‑8, cyclooxygenase (COX)‑2 and intercellular adhesion molecule‑1 (ICAM‑1), and inhibited IL‑1β‑induced increases in the expression of IL‑6, IL‑8, ICAM‑1 and COX‑2. The levels of prostaglandin E2 in orbital fibroblasts induced by IL‑1β were also suppressed by celastrol. Further investigation revealed that celastrol suppressed the IL‑1β‑induced inflammatory responses in orbital fibroblasts through inhibiting the activation of nuclear factor (NF)‑κB. Taken together, these results suggested that celastrol attenuated the IL‑1β‑induced pro‑inflammatory pathway in orbital fibroblasts from patients with GO, which was associated with the suppression of NF-κB activation.

Pentraxin-3 Is a TSH-Inducible Protein in Human Fibrocytes and Orbital Fibroblasts

CD34(+) fibrocytes are bone marrow-derived monocyte progenitor cells that traffic to sites of tissue injury and repair. They putatively infiltrate the orbit in thyroid-associated ophthalmopathy where they appear to transition into CD34(+) orbital fibroblasts (OFs) that interact with residential CD34(-) fibroblasts. A unique phenotypic attribute of fibrocytes and CD34(+) OFs is their expression of the functional thyrotropin receptor (TSHR) and other "thyroid-specific" proteins. When activated through TSHR, fibrocytes express a number of cytokines and other inflammatory genes. Here we sought to determine whether pentraxin-3 (PTX-3), an acute-phase protein involved in inflammation and autoimmunity, might be induced by TSH in fibrocytes and OFs. These cells were collected from patients with Graves disease and healthy individuals. PTX-3 mRNA levels were determined by real-time PCR, protein was determined by ELISA and Western blot, and PTX-3 gene promoter activity was assessed with reporter assays. PTX-3 expression was induced by TSH in both cell types, regardless of the health status of the donor and was a consequence of increased steady-state PTX-3 mRNA levels. M22, a TSHR-activating monoclonal antibody, also induced PTX-3. The induction could be attenuated by dexamethasone and by IGF-I receptor-blocking antibodies, teprotumumab and 1H7. TSH effects were mediated through phosphatidylinositol 3-kinase/AKT, mammalian target of rapamycin/p70(s6k), Janus tyrosine kinase 2 pathways, and enhanced PTX-3 mRNA stability. These findings indicate that PTX-3 is a TSH target gene, the expression of which can be induced in fibrocytes and OFs. They suggest that PTX-3 might represent a previously unidentified nexus between the thyroid axis and the mechanisms involved in tissue remodeling.

CD40 ligand induces expression of vascular cell adhesion molecule 1 and E-selectin in orbital fibroblasts from patients with Graves' orbitopathy

PURPOSE

The aim of this study was to detect the effect of the CD40 ligand (CD40L) on the expression of vascular cell adhesion molecule 1 (VCAM-1) and E-Selectin in orbital fibroblasts (OFs) from patients with Graves' orbitopathy (GO), as well as the signaling pathways involved in this effect.

METHODS

OFs were isolated from orbital tissues obtained from patients with severe GO who were undergoing orbital decompression surgery. VCAM-1 and E-selectin RNA and protein expression levels were quantified in OFs stimulated with soluble CD40L (sCD40L). RNA and protein quantification was performed with real-time polymerase chain reaction (PCR) and western blot analysis. Cytoplasmic and nuclear fractions were isolated in order to detect the nuclear translocation of nuclear factor-κB (NF-κB). Signaling pathway inhibitors were applied to determine the pathways involved.

RESULTS

Compared to unstimulated OFs, the mRNA and protein levels of VCAM-1 and E-selectin in OFs incubated with sCD40L were significantly increased. This was observed in dose- and time-course experiments, and the inductive effects of sCD40L were much weaker in OFs from healthy donors. At the same time, we observed that CD40L induced nuclear translocation of NF-κB, also in a dose- and time-dependent manner. The up-regulation of VCAM-1 and E-selectin, as well as the NF-κB nuclear translocation induced by CD40L, was significantly attenuated by inhibitors targeting mitogen-activated protein kinases (MAPKs), phosphatidylinositol 3-kinase (PI3K), and NF-κB.

CONCLUSIONS

CD40L demonstrated the ability to up-regulate the expression of VCAM-1 and E-selectin at the pre-translational level in OFs from patients with GO. The MAPK and PI3K pathways and NF-κB may play important roles in CD40L-induced VCAM-1 and E-selectin expression.

PGE2 induces IL-6 in orbital fibroblasts through EP2 receptors and increased gene promoter activity: implications to thyroid-associated ophthalmopathy

Background

IL-6 plays an important role in the pathogenesis of Graves' disease and its orbital component, thyroid-associated ophthalmopathy (TAO). Orbital tissues become inflamed in TAO, a process in which prostanoids have been implicated. Orbital fibroblasts both generate and respond to PGE₂, underlying the inflammatory phenotype of these cells.

Methodology/Principal Findings

Using cultured orbital and dermal fibroblasts, we characterized the effects of PGE₂ on IL-6 expression. We found that the prostanoid provokes substantially greater cytokine synthesis in orbital fibroblasts, effects that are mediated through cell-surface EP₂ receptors and increased steady-state IL-6 mRNA levels. The pre-translational up-regulation of IL-6 results from increased gene promoter activity and can be reproduced with the PKA agonist, Sp-cAMP and blocked by interrupting the PKA pathway. PGE₂-induced production of cAMP in orbital fibroblasts was far greater than that in dermal fibroblasts, resulting from higher levels of adenylate cyclase. PGE₂ provokes CREB phosphorylation, increases the pCREB/CREB ratio, and initiates nuclear localization of the pCREB/CREB binding protein/p300 complex (CBP) preferentially in orbital fibroblasts. Transfection with siRNAs targeting either CREB or CBP blunts the induction of IL-6 gene expression. PGE₂ promotes the binding of pCREB to its target DNA sequence which is substantially greater in orbital fibroblasts.

Conclusion/Significance

These results identify the mechanism underlying the exaggerated induction of IL-6 in orbital fibroblasts and tie together two proinflammatory pathways involved in the pathogenesis of TAO. Moreover, they might therefore define an attractive therapeutic target for the treatment of TAO.

The origin of fibroblasts and mechanism of cardiac fibrosis

Fibroblasts are at the heart of cardiac function and are the principal determinants of cardiac fibrosis. Nevertheless, cardiac fibroblasts remain poorly characterized in molecular terms. Evidence is evolving that the cardiac fibroblast is a highly heterogenic cell population, and that such heterogeneity is caused by the distinct origins of fibroblasts in the heart. Cardiac fibroblasts can derive either from resident fibroblasts, from endothelial cells via an endothelial-mesenchynmal transition or from bone marrow-derived circulating progenitor cells, monocytes and fibrocytes. Here, we review the function and origin of fibroblasts in cardiac fibrosis.NB. The information given is correct.

Thyroid eye disease: honing your skills to improve outcomes

Thyroid eye disease affects the eyelids, orbital compartment, and extraocular muscles, resulting in a highly variable degree of chemosis and enlargement of the preorbital fat pads, eyelid retraction, proptosis, restrictive strabismus, torticollis, and, rarely, compressive or congestive optic neuropathy. Although most patients with thyroid eye disease are best treated conservatively, those more severely affected may benefit from orbital decompression, strabismus surgery, or eyelid retraction repair after stabilization has occurred. Botulinum A toxin, high-dose intravenous corticosteroids, and radiation treatment are therapeutic options in select cases. Compressive or congestive optic neuropathy and severe corneal exposure warrant consideration of surgical intervention on an urgent basis without waiting for stabilization. Epidemiology and risks and benefits of high-dose steroids and radiation therapy are reviewed along with recommendations to improve conservative as well as surgical management of this disease. Strategies to manage strabismus and optimize outcomes are provided.

Perimysial fibroblasts of extraocular muscle, as unique as the muscle fibers

PURPOSE

Extraocular muscle (EOM) has a distinct skeletal muscle phenotype. The hypothesis for the study was that fibroblasts support the unique EOM phenotype and that perimysial fibroblasts derived from EOM have properties that distinguish them from fibroblasts derived from other skeletal muscle.

METHODS

Perimysial fibroblasts from leg muscle (LM-Fibro) and EOM (EOM-Fibro) of mice were derived and maintained in culture. EOM- and LM-Fibro were assessed morphologically and for vimentin, smooth muscle actin, and Thy-1 immunoreactivity. DNA microarray analysis was performed on LM- and EOM-Fibro grown in conditions that support myoblast differentiation. To assess trophic interactions, co-cultures of myoblasts from established cell lines, CL-EOM and CL-LM with, EOM- or LM-Fibro were performed in direct contact and in a permeable filter support culture. The degree of myotube maturation was assessed by the percentage of myotubes with more than three myonuclei per myotube.

RESULTS

EOM- and LM-Fibro cells exhibited distinct morphologies. Both cell types proliferated as a monolayer and expressed vimentin. Fifty-five percent (SD 4.4%) of EOM-Fibro were Thy-1 positive compared with only 24% (SD 4.4%) of LM-Fibro. DNA microarray analysis demonstrated differential expression of structural, immune response, and metabolism-related genes between EOM- and LM-Fibro. Co-cultures demonstrated that mature myotube formation in EOM-derived cell lines was supported to a greater extent by EOM-Fibro than by LM-Fibro, compared with CL-EOM grown with LM-Fibro.

CONCLUSIONS

Fibroblasts from EOM demonstrate distinct properties that distinguish them from leg muscle-derived fibroblasts. The distinct properties of EOM-Fibro may support the unique EOM phenotype and contribute to their differential involvement in disease.

Histologic features of mesotherapy-induced orbital fat inflammation

A 67-year-old man developed acute orbital inflammation after receiving cosmetic mesotherapy (Lipo-Dissolve) to the inferior orbital fat compartments. The injection was intended to cause lipolysis and shrinkage of fat lobules with subsequent cosmetic improvement. Injections of a mixture of bile salts, phospholipid, and alcohol preservative bilaterally in inferior orbital fat lobules led to an acute inflammatory reaction characterized histologically 12 days later by mild lymphocytic infiltration, fat necrosis, and fibrosis in the target areas. Benign proliferation of peripheral nerve trunks consistent with a traumatic neuroma was also noted histologically on one side. Inflammation including fat necrosis and traumatic neuroma are all possible consequences of mesotherapy.

Oral montelukast and cetirizine for thyroid eye disease

PURPOSE

To study the efficacy of oral montelukast, a cysteinyl leukotriene receptor antagonist, in combination with cetirizine, a histamine-1 receptor antagonist, in the treatment of thyroid eye disease.

METHODS

Patients considering surgical correction of eyelid retraction for inflammatory symptoms of thyroid eye disease were offered a preoperative medical regimen of oral montelukast/cetirizine. Exclusion criteria included prior use of oral montelukast (i.e., for seasonal allergy or asthma), compressive optic neuropathy, severe ophthalmopathy requiring systemic corticosteroids, and orbital and/or muscle surgery. A 6-week course of oral cetirizine (10 mg every morning) and oral montelukast (10 mg every evening) was administered and patients subjectively rated their ocular surface dryness, tearing, itching, injection, eyelid swelling, eyelid retraction, double vision, proptosis, and visual clarity, at baseline, after 3 weeks and 6 weeks of medical therapy, and after 3 weeks off of the medications.

RESULTS

Six of the 12 patients recruited for the study reported a subjective improvement in tearing, dryness, and itching. Less effect on diplopia and proptosis was noted after 6 weeks of medical therapy. Two of the patients who did not report response chose to proceed with eyelid retraction surgery and both had evidence of mast cell infiltration in their Müller muscle specimens.

CONCLUSION

The response observed in this open-label trial suggests that oral montelukast and cetirizine may be an effective medical regimen for patients with thyroid eye disease who experience mild to moderate orbital congestion and inflammation.

Characterisation of 11beta-hydroxysteroid dehydrogenase 1 in human orbital adipose tissue: a comparison with subcutaneous and omental fat

Glucocorticoids (GCs) have a profound effect on adipose biology increasing tissue mass causing central obesity. The pre-receptor regulation of GCs by 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) that activates cortisol from cortisone has been postulated as a fundamental mechanism underlying the metabolic syndrome mediating adipocyte hyperplasia and hypertrophy in the omental (OM) depot. Orbital adipose tissue (OF) is the site of intense inflammation and tissue remodelling in several orbital inflammatory disease states. In this study, we describe features of the GC metabolic pathways in normal human OF depot and compare it with subcutaneous (SC) and OM depots. Using an automated histological characterisation technique, OF adipocytes were found to be significantly smaller (parameters: area, maximum diameter and perimeter) than OM and SC adipocytes (P<0 x 001). Although immunohistochemical analyses demonstrated resident CD68+ cells in all three whole tissue adipose depots, OF CD68 mRNA and protein expression exceeded that of OM and SC (mRNA, P<0 x 05; protein, P<0 x 001). In addition, there was higher expression of glucocorticoid receptor (GR)alpha mRNA in the OF whole tissue depot (P<0 x 05). Conversely, 11beta-HSD1 mRNA together with the markers of late adipocyte differentiation (FABP4 and G3PDH) were significantly lower in OF. Primary cultures of OF preadipocytes demonstrated predominant 11beta-HSD1 oxo-reductase activity with minimal dehydrogenase activity. Orbital adipocytes are smaller, less differentiated, and express low levels of 11beta-HSD1 but abundant GRalpha compared with SC and OM. OF harbours a large CD68+ population. These characteristics define an orbital microenvironment that has the potential to respond to sight-threatening orbital inflammatory disease.

Prominent Premalar and Cheek Swelling: A Sign of Thyroid-associated Orbitopathy

PURPOSE

To describe prominent premalar and cheek swelling as a previously undescribed clinical feature of thyroid-associated orbitopathy (TAO).

DESIGN

Retrospective interventional case series.

METHODS

A retrospective case review of patients with prominent premalar and/or cheek swelling and TAO was undertaken. All patients who presented from March 2002 to February 2005 with complaints of premalar and/or cheek swelling in TAO were analyzed.

RESULTS

Six female patients between the ages of 28 and 66 years (average, 44.2 years) who had complaints of prominent premalar and/or cheek swelling and TAO were included in the study, among 326 new patients with TAO (incidence: 1.84%). Five of the 6 patients had Graves hyperthyroidism. One initially had Hashimoto thyroiditis, which converted to Graves hyperthyroidism. In all cases, TAO preceded the thyroid disease or developed simultaneously (average time from TAO to thyroid disease was 3.0 months). No patient had received corticosteroids before premalar and/or cheek swelling. The premalar and/or cheek swelling was bilateral in all cases, but 2 of 6 were asymmetric. No diurnal fluctuation or tenderness in premalar and/or cheek swelling was noted. All improved incompletely over several months. Brow, eyelid swelling, and orbital-fat hypertrophy on radiologic examination was coincidentally noted in 5 of 6 cases. Pretibial myxedema was noted in one case. One case was associated with another autoimmune disease (rheumatoid arthritis).

CONCLUSIONS

Prominent premalar and cheek swelling should be considered among the clinical features of TAO. The true incidence will become apparent as we question and examine patients more carefully regarding this entity and as we review premorbid photographs.

Role of adipose tissue as an inflammatory organ in human diseases

Reviews on the inflammatory role of adipose tissue outside the field of metabolism are rare. There is increasing evidence provided by numerous basic research studies from nearly all internal medicine subspecializations that adipocytes and adipocytokines are involved in primary inflammatory processes and diseases. Therefore, it is the aim of the present review to discuss and to summarize the current knowledge on the inflammatory role of adipocytokines and special types of regional adipocytes such as retroorbital, synovial, visceral, subdermal, peritoneal, and bone marrow adipocytes in internal medicine diseases. Future clinical and therapeutic implications are discussed.

Graves' ophthalmopathy: state of the art and perspectives

Graves' ophthalmopathy (GO) is an autoimmune orbital disorder most commonly associated with Graves' disease. Recent studies have underscored the role that orbital cells, particularly fibroblasts and adipocytes, play in causing the increase in orbital content responsible for clinical manifestations of the disease. GO seems to be related to autoimmune reactions triggered by autoreactive T lymphocytes of thyroid origin, which recognize antigen(s) shared by thyroid and orbit. The nature of the antigen (or antigens) involved is not fully understood, but TSH receptor is likely to be involved. Cytokines secreted by T lymphocytes, macrophages and fibroblasts play an essential role in perpetuating the disease. Animal models of GO have been developed, but results have not clarified GO pathogenesis yet. Progress in the management of the ophthalmopathy has been very limited, and glucocorticoids, orbital radiotherapy and orbital decompression remain the mainstays in GO treatment. Novel treatments, such as somatostatin analogues, antioxidants, cytokine antagonists are currently under investigation, as well as the effects of total thyroid ablation. Cessation of smoking currently represents the only form of GO (secondary and tertiary) prevention.